Golf Ball Having Outer Cover With Low Flexural Modulus

ABSTRACT

A golf ball having an outer cover layer with a lower flexural modulus than that of an inner core layer and/or an inner cover layer is disclosed. The lower flexural modulus of the outer cover layer may give the golf ball a good feel during short shots and putting. The inner cover layer may have a first flexural modulus and the outer cover layer may have a second flexural modulus. The first flexural modulus may be at least about 10 times greater than the second flexural modulus. The inner core layer may have a third flexural modulus. The third flexural modulus may be at least about 5 times greater than the second flexural modulus.

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/526,557, entitled “Golf BallHaving Outer Cover With Low Flexural Modulus”, and filed on Aug. 23,2011, which application is hereby incorporated by reference.

BACKGROUND

The present invention relates generally to a golf ball having differentplay characteristics in different situations.

The game of golf is an increasingly popular sport at both amateur andprofessional levels. A wide range of technologies related to themanufacture and design of golf balls are known in the art. Suchtechnologies have resulted in golf balls with a variety of playcharacteristics. For example, some golf balls have a better flightperformance than other golf balls. Some golf balls with a good flightperformance do not have a good feel when hit with a golf club. Thus, itwould be advantageous to make a golf ball with a good flight performancethat also has a good feel.

SUMMARY

A golf ball having an outer cover layer with a lower flexural modulusthan that of an inner core layer and/or an inner cover layer isdisclosed. The lower flexural modulus of the outer cover layer may givethe golf ball a good feel during short shots and putting.

In one aspect, the disclosure provides a golf ball that may have aninner core layer, an outer core layer enclosing the inner core layer, aninner cover layer enclosing the outer core layer, and an outer coverlayer enclosing the inner cover layer. The inner cover layer may have afirst flexural modulus and the outer cover layer may have a secondflexural modulus. The first flexural modulus may be at least 10 timesgreater than said second flexural modulus. The ratio between the firstflexural modulus and the second flexural modulus (first flexuralmodulus/second flexural modulus) may range from about 10 to about 30.The ratio between the first flexural modulus and the second flexuralmodulus (first flexural modulus/second flexural modulus) may range fromabout 10 to about 30. The ratio between the first flexural modulus andthe second flexural modulus (first flexural modulus/second flexuralmodulus) may range from about 95 to about 250. The inner core layer mayinclude a third flexural modulus and the ratio of third flexural modulusto second flexural modulus (third flexural modulus/second flexuralmodulus) may range from about 5 to about 10. The inner core layer mayinclude a first highly neutralized acid polymer composition. The innercore layer may have a coefficient of restitution value ranging fromabout 0.775 to about 0.81. The inner core layer may have a coefficientof restitution value that is about 0.005 to about 0.02 greater than thecoefficient of restitution value of the golf ball. The inner cover layermay have a Shore D hardness ranging from about 45 to about 55.

In one aspect, the disclosure provides a golf ball that may have aninner core layer, an outer core layer enclosing the inner core layer, aninner cover layer enclosing the outer core layer, and an outer coverlayer enclosing the inner cover layer. The inner core may have a firstflexural modulus and the outer cover layer may have a second flexuralmodulus. The first flexural modulus may be at least about 5 timesgreater than the second flexural modulus. The ratio of first flexuralmodulus to second flexural modulus (first flexural modulus/secondflexural modulus) may range from about 5 to about 10. The inner coverlayer may have a third flexural modulus and the ratio between the thirdflexural modulus and the second flexural modulus (third flexuralmodulus/second flexural modulus) may range from about 10 to about 30.The inner core layer may include a first highly neutralized acid polymercomposition. The first highly neutralized acid polymer compositionincludes one of HPF 2000 and HPF AD 1035. The inner core layer mayinclude a first highly neutralized acid polymer composition and a secondhighly neutralized acid polymer composition and the ratio of the firsthighly neutralized acid polymer composition to the second highlyneutralized acid polymer composition may range from about 20:80 to about80:20. The inner core layer may have a coefficient of restitution valuethat is about 0.005 to about 0.02 greater than the coefficient ofrestitution value of the golf ball.

In one aspect, the disclosure provides a golf ball that may have aninner core layer, an outer core layer enclosing the inner core layer, aninner cover layer enclosing the outer core layer, and an outer coverlayer enclosing the inner cover layer. The inner cover layer may have afirst flexural modulus and the outer cover layer may have a secondflexural modulus. The first flexural modulus may be at least about45,000 psi greater than the second flexural modulus. The first flexuralmodulus may be between about 60,000 psi and about 95,000 psi greaterthan the second flexural modulus. The inner core layer may include athird flexural modulus and the third flexural modulus may be betweenabout 15,000 psi to 65,000 psi greater than the second flexural modulus.

Other systems, methods, features and advantages of the invention willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the invention, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 illustrates the trajectory of a golf ball prepared according tothe present disclosure compared with the trajectory of a different typeof golf ball after being hit by a driver;

FIG. 2 illustrates the trajectory of a golf ball prepared according tothe present disclosure after being hit by a pitching wedge; an

FIG. 3 is a golf ball according to the exemplary embodiment of FIGS. 1and 2.

DETAILED DESCRIPTION

Generally, the present disclosure relates to a golf ball having avariable initial velocity associated with striking the golf ball with adriver having different head speeds. The structure of the disclosed golfball may cause the golf ball to experience an initial velocitycomparable to premium golf balls currently on the market when hit with adriver head speed less than 100 mph. However, the same golf ball mayexperience an initial velocity higher than premium golf balls currentlyon the market when hit with a driver head speed higher than 125 mph. Asa result, the disclosed golf ball may have different initial velocitiesassociated with different head speeds.

FIGS. 1-2 show an exemplary embodiment of a golf ball 100. In FIG. 1, arecreational golfer 142 has used a driver 144 to hit golf ball 100 andanother type of golf ball, golf ball 182, off of a tee 146 located in atee box 148. As a typical recreational golfer, golfer 142 hits golf ball100 and golf ball 182 with a driver head speed of less than 100 mph.FIG. 1 demonstrates a comparison between a trajectory 150 of golf ball100 and a trajectory 180 of golf ball 182 after each of the golf ballshave been struck by driver 144. Each of the golf balls has a comparabletrajectory length because each of the golf balls has a similar initialvelocity associated with being hit by driver 144 with a driver headspeed of less than 100 mph. Trajectory 150 extends about as long astrajectory 180 because golf ball 100 has a similar initial velocity asgolf ball 182 after being struck by driver 144 with a driver head speedof less than 100 mph.

In FIG. 2, a professional golfer 152 has used a driver 144 to hit golfball 100 and another type of golf ball, golf ball 182, off of a tee 146located in a tee box 148. As a typical professional golfer, golfer 152hits golf ball 100 and golf ball 182 with a driver head speed of morethan 125 mph. FIG. 2 demonstrates a comparison between a trajectory 160of golf ball 100 and a trajectory 162 of golf ball 182 after each of thegolf balls have been struck by driver 144. Trajectory 160 is longer thantrajectory 162 because golf ball 100 and golf ball 182 each have adifferent initial velocity associated with being hit by driver 144 witha driver head speed of more than 125 mph. When struck by driver 144 witha driver head speed of more than 125 mph, golf ball 100 has a higherinitial velocity than that of golf ball 182 and, in turn, golf ball 100flies further than golf ball 182.

Tables 3-6 show the results of tests performed on test balls, whichinclude golf balls prepared according to the present disclosure andexisting golf balls currently available on the market. The golf ballsprepared according to the present disclosure includes Example 1, detailsof which are shown in Table 1. Materials A, B, C, and D are discussed inmore detail with reference to Tables 8-11. The existing golf ballscurrently available on the market include Comparative Examples 1-4,details of which are shown in Table 2 (where PBR is polybutadienerubber). The results shown in Tables 3-6 include initial velocity (IV)and launch angle (LA). All results for IV have an uncertainty of ±1 mph.

TABLE 1 Golf Ball Testing Data 1 Inner Core Layer Material A Diameter(mm) 24 Shore D Hardness 53 Compression 3.2 Deformation (mm) COR 0.83Outer Core Layer Material B Thickness (mm) 7.25 Shore D Hardness 59Inner Cover Layer Material C Thickness (mm) 1.0 Shore D Hardness 69Flexural Modulus 77,000 (psi) Outer cover layer Material D Thickness(mm) 1.1 Shore D Hardness 53 Flexural 550 Modulus (psi) Entire Ball COR0.785

TABLE 2 Comparative Test Balls Ball Name and Brand Ball Pieces CoreCover ProV1 by Titleist Comparative Five (5) PBR Urethane Example 1 Touri(s) by Comparative Three (3) PBR Urethane Callaway Example 2 ONE Tourby Nike Comparative Three (3) PBR Urethane Golf Example 3 ONE Tour D byComparative Three (3) PBR Urethane Nike Golf Example 4

The tests performed on the test balls were conducted as follows: a NikeSQ Dymo driver (loft angle: 10.5°; shaft: Diamana by Mitsubishi Rayon;flex: X (extra stiff); grip: golf pride) was fixed to a swing robotmanufactured by Miyamae Co., Ltd. and then swung at different headspeeds from about 80 mph to about 125 mph. The clubface was oriented fora square hit. The forward/backward tee position was adjusted so that thetee was three inches in front of the point in the downswing where theclub was vertical. The height of the tee and the toe-heel position ofthe club relative to the tee were adjusted such that the center of theimpact mark was centered toe to heel across the face.

Table 3 shows the results of the 125 mph head speed test. The 125 mphhead speed test involves hitting the test balls with a driver having ahead speed of about 125 mph±1 mph. The driver used in the test of Table3 is described above. The calibration ball for the 125 mph head speedtest is a ONE Tour D golf ball commercially available by Nike Golf. Tocalibrate the 125 mph head speed test, the conditions are set to causethe calibration ball to have an initial velocity of 171 mph±1 mph whenthe calibration ball is hit with the driver having a head speed of about125 mph±1 mph.

The results show that, for the 125 mph head speed test, the InitialVelocity of golf balls prepared according to the present disclosure arehigher than the Initial Velocity of the existing golf balls currentlyavailable on the market. For example, Comparative Example 2 has anInitial Velocity of about 171 mph. In contrast, Example 1 has a higherInitial Velocity of about 174 mph. The next highest Initial Velocityresulting from the 125 mph head speed test came from ComparativeExample 1. At about 172.5 mph, this Initial Velocity is still less thanthe Initial Velocity of Example 1.

TABLE 3 125 MPH DRIVER Ball Name Initial Velocity (IV) (mph) and BrandBall of Samples N/A Example 1 174 ProV1 by Comparative 172.5 TitleistExample 1 Tour i(s) by Comparative 171 Callaway Example 2a ONE Tour byComparative 171.5 Nike Golf Example 3a ONE Tour D Comparative 171 byNike Golf Example 4a

Table 4 shows the results of the 110 mph head speed test. The 110 mphhead speed test involves hitting the test balls with a driver having ahead speed of about 110 mph±1 mph. The driver used in the test of Table4 is described above. The calibration ball for the 110 mph head speedtest is a ONE Tour D golf ball commercially available by Nike Golf. Tocalibrate the 110 mph head speed test, the conditions are set to causethe calibration ball to have an initial velocity of 159 mph±1 mph whenthe calibration ball is hit with the driver having a head speed of about110 mph±1 mph.

The results show that, for the 110 mph head speed test, the InitialVelocity of golf balls prepared according to the present disclosure arecomparable to the Initial Velocity of the existing golf balls currentlyavailable on the market. For example, Comparative Example 2 has anInitial Velocity of about 159 mph. Similarly, Example 1 has an InitialVelocity of about 159.5 mph. The Initial Velocities of the ComparativeExamples resulting from the 110 mph head speed test were all withinabout 157 mph and about 159.5 mph.

TABLE 4 110 MPH DRIVER Ball Name Initial Velocity (IV) (mph) and BrandBall of Samples N/A Example 1 159.5 ProV1 by Comparative Example 1 159Titleist Tour i(s) by Comparative Example 2 157 Callaway ONE Tour byComparative Example 3 159.5 Nike Golf ONE Tour D Comparative Example 4159 by Nike Golf

Table 5 shows the results of the 95 mph head speed test. The 95 mph headspeed test involves hitting the test balls with a driver having a headspeed of about 95 mph±1 mph. The driver used in the test of Table 5 isdescribed above. The calibration ball for the 95 mph head speed test isa ONE Tour D golf ball commercially available by Nike Golf. To calibratethe 95 mph head speed test, the conditions are set to cause thecalibration ball to have an initial velocity of 116.5 mph±1 mph when thecalibration ball is hit with the driver having a head speed of about 95mph±1 mph.

The results show that, for the 95 mph head speed test, the InitialVelocity of golf balls prepared according to the present disclosure arecomparable to the Initial Velocity of the existing golf balls currentlyavailable on the market. For example, Comparative Example 1 has anInitial Velocity of about 116 mph. Similarly, Example 1 has an InitialVelocity of about 116 mph. The Initial Velocities of the ComparativeExamples resulting from the 95 mph head speed test were all either about116 mph or about 116.5 mph.

TABLE 5 95 MPH DRIVER Ball Name Initial Velocity (IV) (mph) and BrandBall of Samples N/A Example 1 116 ProV1 by Comparative Example 1 116Titleist Tour i(s) by Comparative Example 2 116.5 Callaway ONE Tour byComparative Example 3 116 Nike Golf ONE Tour D Comparative Example 4116.5 by Nike Golf

Table 6 shows the results of the 80 mph head speed test. The 80 mph headspeed test involves hitting the test balls with a driver having a headspeed of about 80 mph±1 mph. The driver used in the test of Table 4 isdescribed above. The calibration ball for the 80 mph head speed test isa ONE Tour D golf ball commercially available by Nike Golf. To calibratethe 80 mph head speed test, the conditions are set to cause thecalibration ball to have an initial velocity of 89.5 mph±1 mph when thecalibration ball is hit with the driver having a head speed of about 80mph±1 mph.

The results show that, for the 80 mph head speed test, the InitialVelocity of golf balls prepared according to the present disclosure arecomparable to the Initial Velocity of the existing golf balls currentlyavailable on the market. For example, Comparative Example 1 has anInitial Velocity of about 88 mph. Similarly, Example 1 has an InitialVelocity of about 88 mph. The Initial Velocities of the ComparativeExamples resulting from the 80 mph head speed test were all within about87.5 mph or about 89.5 mph.

TABLE 6 80 MPH DRIVER Ball Name Initial Velocity (IV) (mph) and BrandBall of Samples N/A Example 1 88 ProV1 by Comparative Example 1 88Titleist Tour i(s) by Comparative Example 2 87.5 Callaway ONE Tour byComparative Example 3 89 Nike Golf ONE Tour D Comparative Example 4 89.5by Nike Golf

Table 7 shows the differences between initial velocities resulting fromstriking the test balls with a driver under different head speeds.

TABLE 7 DIFFERENCES IN INITIAL VELOCITIES Difference in Difference inInitial Difference in Initial Velocities Velocities Resulting InitialVelocities Ball Name Resulting from 95 mph from 110 mph and Resultingfrom and Brand Ball and 80 mph 80 mph 125 mph and 80 mph N/A Example 128 mph 71.5 mph   86 mph ProV1 by Comparative 28 mph   71 mph 84.5 mphTitleist Example 1 Tour i(s) by Comparative 29 mph 69.5 mph 83.5 mphCallaway Example 2 ONE Tour by Comparative 27 mph 70.5 mph 82.5 mph NikeGolf Example 3 ONE Tour D Comparative 27 mph 69.5 mph 81.5 mph by NikeGolf Example 4

As used herein, unless otherwise stated, compression, hardness, COR, andflexural modulus are measured as follows:

Compression deformation: The compression deformation herein indicatesthe deformation amount of the ball under a force; specifically, when theforce is increased to become 130 kg from 10 kg, the deformation amountof the ball under the force of 130 kg subtracts the deformation amountof the ball under the force of 10 kg to become the compressiondeformation value of the ball.

Hardness: Hardness of golf ball layer is measured generally inaccordance with ASTM D-2240, but measured on the land area of a curvedsurface of a molded ball. For material hardness, it is measured inaccordance with ASTM D-2240 (on a plaque).

Method of measuring COR: A golf ball for test is fired by an air cannonat an initial velocity of 40 m/sec, and a speed monitoring device islocated over a distance of 0.6 to 0.9 meters from the cannon. Whenstriking a steel plate positioned about 1.2 meters away from the aircannon, the golf ball rebounds through the speed-monitoring device. Thereturn velocity divided by the initial velocity is the COR.

As shown in FIG. 3, golf ball 100 may include an inner core layer 110,an outer core layer 120, an inner cover layer 130, and an outer coverlayer 140. While the exemplary embodiment of golf ball 100 has beendescribed and illustrated as having four layers, other embodiments mayinclude any number of layers. For example, in some embodiments, golfball 100 may be a one-piece, two-piece, three-piece, or five-piece ball.In some embodiments, golf ball 100 may include more than five layers.The number of layers may be selected based on a variety of factors. Forexample, the number of layers may be selected based on the type ofmaterials use to make the golf ball and/or the size of the golf ball.

The type of materials used to make the layers of the golf ball may beselected based on a variety of factors. For example, the type ofmaterials used to make the layers of the golf ball may be selected basedon the properties of the material and/or the processes used to form thelayers. Exemplary materials are discussed below with respect to theindividual layers of the exemplary embodiment. In some embodiments, oneor more layers may be made from different materials. In someembodiments, one or more layers may be made from the same materials.

The golf ball may be made by any suitable process. The process of makingthe golf ball may be selected based on a variety of factors. Forexample, the process of making the golf ball may be selected based onthe type of materials used and/or the number of layers included.Exemplary processes are discussed below with respect to the individuallayers of the exemplary embodiment.

In some embodiments, inner core layer 110 may have a diameter rangingfrom 19 mm to 32 mm. In some embodiments, inner core layer 110 may havea diameter ranging from 20 mm to 30 mm. In some embodiments, inner corelayer 110 may have a diameter ranging from 21 mm to 28 mm. In someembodiments, the diameter of inner core layer 110 may be at least threetimes greater than the thickness of outer core layer 120.

Inner core layer 110 may be made by any suitable process. For example,in some embodiments, inner core layer 110 may be made by an injectionmolding process. During injection molding process, the temperature ofthe injection machine may be set within a range of about 190° C. toabout 220° C. In some embodiments, before the injection molding process,the at least two highly neutralized acid polymer compositions may bekept sealed in a moisture-resistant dryer capable of producing dry air.Drying conditions for the highly neutralized acid polymer compositionmay include 2 to 24 hours at a temperature below 50° C. In someembodiments, inner core layer 110 may be made by a compression moldingprocess. The process of making the inner core layer may be selectedbased on a variety of factors. For example, the process of making theinner core layer may be selected based on the type of material used tomake the inner core layer and/or the process used to make the otherlayers.

In some embodiments, inner core layer 110 may include one or more highlyneutralized acid polymer compositions. For example, in the exemplaryembodiments, inner core layer 110 may include two highly neutralizedacid polymer compositions. In some embodiments, the ratio of a firsthighly neutralized acid polymer composition to a second highlyneutralized acid polymer composition may range from 20:80 to 80:20. Inanother embodiment, the same ratio may range from 30:70 to 70:30. Inanother embodiment, the same ratio may range from 40:60 to 60:40. In yetanother embodiment, the same ratio same ratio may be 50:50. In someembodiments, two highly neutralized acid polymer compositions eachhaving a flexural modulus of ranging from 20,000 psi to 35,000 psi maybe used to make inner core layer 110. In some embodiments, two highlyneutralized acid polymer compositions each having a Vicat softeningtemperature of from 50° C. to 60° C., or 52° C. to 58° C. may be used tomake inner core layer 110. In some embodiments, suitable materials forthe inner core layer may include the following highly neutralized acidpolymer compositions: HPF resins such as HPF1000, HPF2000, HPF AD1024,HPF AD1027, HPF AD1030, HPF AD1035, HPF AD1040, all produced by E. I.Dupont de Nemours and Company.

Table 8 provides an example of materials used to make inner core layer110, according to the exemplary embodiment. The amounts of the materialslisted in Table 8 are shown in parts by weight (pbw).

TABLE 8 Inner Core Layer Materials Resin: A HPF 2000 66 HPF AD 1035 34

In some embodiments, the material used to form inner core layer 110 mayinclude a highly neutralized acid polymer composition and optionaladditives, fillers, and/or melt flow modifiers. The acid polymer may beneutralized to 80% or higher, including up to 100%, with a suitablecation source, such as magnesium, sodium, zinc, or potassium. In theexemplary embodiment, the highly neutralized acid polymer compositionsused to make the inner core layer may include the same cation source.Suitable additives and fillers may include, for example, blowing andfoaming agents, optical brighteners, coloring agents, fluorescentagents, whitening agents, UV absorbers, light stabilizers, defoamingagents, processing aids, mica, talc, nanofillers, antioxidants,stabilizers, softening agents, fragrance components, plasticizers,impact modifiers, acid copolymer wax, surfactants. Suitable fillers mayalso include inorganic fillers, such as zinc oxide, titanium dioxide,tin oxide, calcium oxide, magnesium oxide, barium sulfate, zinc sulfate,calcium carbonate, zinc carbonate, barium carbonate, mica, talc, clay,silica, lead silicate. Suitable fillers may also include high specificgravity metal powder fillers, such as tungsten powder and molybdenumpowder. Suitable melt flow modifiers may include, for example, fattyacids and salts thereof, polyamides, polyesters, polyacrylates,polyurethanes, polyethers, polyureas, polyhydric alcohols, andcombinations thereof.

In some embodiments, outer core layer 120 may be formed primarily of athermoset material. For example, outer core layer 120 may be formed bycrosslinking a polybutadiene rubber composition as described in U.S.patent application Ser. No. 12/827,360, entitled Golf Balls IncludingCrosslinked Thermoplastic Polyurethane, filed on Jun. 30, 2010, andapplied for by Chien-Hsin Chou et al., the disclosure of which is herebyincorporated by reference in its entirety. When other rubber is used incombination with a polybutadiene, polybutadiene may be included as aprincipal component. For example, in some embodiments, a proportion ofpolybutadiene in the entire base rubber may be equal to or greater than50% by weight. In some embodiments, a proportion of polybutadiene in theentire base rubber may be equal to or greater than 80% by weight. Insome embodiments, a polybutadiene having a proportion of cis-1,4 bondsof equal to or greater than 60 mol %, and further, equal to or greaterthan 80 mol % may be used.

In some embodiments, cis-1,4-polybutadiene may be used as the baserubber and mixed with other ingredients to form outer core layer 120. Insome embodiments, the amount of cis-1,4-polybutadiene may be at least 50parts by weight, based on 100 parts by weight of the rubber compound.Various additives may be added to the base rubber to form a compound.The additives may include a cross-linking agent and a filler. In someembodiments, the cross-linking agent may be zinc diacrylate, magnesiumacrylate, zinc methacrylate, or magnesium methacrylate. In someembodiments, zinc diacrylate may provide advantageous resilienceproperties. The filler may be used to increase the specific gravity ofthe material. The filler may include zinc oxide, barium sulfate, calciumcarbonate, or magnesium carbonate. In some embodiments, zinc oxide maybe selected for its advantageous properties. Metal powder, such astungsten, may alternatively be used as a filler to achieve a desiredspecific gravity. In some embodiments, the specific gravity of outercore layer 120 may be from about 1.05 g/cm³ to about 1.45 g/cm³. In someembodiments, the specific gravity of outer core layer 120 may be fromabout 1.05 g/cm³ to about 1.35 g/cm³.

In some embodiments, a polybutadiene synthesized with a rare earthelement catalyst may be used to form outer core layer 120. Such apolybutadiene may provide excellent resilience performance of golf ball100. Examples of rare earth element catalysts include lanthanum seriesrare earth element compound, organoaluminum compound, and almoxane andhalogen containing compounds. Polybutadiene obtained by using lanthanumrare earth-based catalysts usually employs a combination of a lanthanumrare earth (atomic number of 57 to 71) compound, such as a neodymiumcompound.

In some embodiments, a polybutadiene rubber composition having at leastfrom about 0.5 parts by weight to about 5 parts by weight of ahalogenated organosulfur compound may be used to form outer core layer120. In some embodiments, the polybutadiene rubber composition mayinclude at least from about 1 part by weight to about 4 parts by weightof a halogenated organosulfur compound. The halogenated organosulfurcompound may be selected from the group consisting ofpentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol;4-chlorothiophenol; 2,3-chlorothiophenol; 2,4-chlorothiophenol;3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol;3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol;2,3,5,6-tetrachlorothiophenol; pentafluorothiophenol;2-fluorothiophenol; 3-fluorothiophenol; 4-fluorothiophenol;2,3-fluorothiophenol; 2,4-fluorothiophenol; 3,4-fluorothiophenol;3,5-fluorothiophenol 2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenol; pentabromothiophenol; 2-bromothiophenol;3-bromothiophenol 4-bromothiophenol; 2,3-bromothiophenol;2,4-bromothiophenol; 3,4-bromothiophenol; 3,5-bromothiophenol;2,3,4-bromothiophenol; 3,4,5-bromothiophenol;2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol; and theirzinc salts, the metal salts thereof and mixtures thereof.

Table 9 provides an example of materials used to make outer core layer120, according to the exemplary embodiment. The amounts of the materialslisted in Table 9 are shown in parts by weight (pbw). TAIPOL™ BR0150 isthe trade name of a rubber produced by Taiwan Synthetic Rubber Corp.

TABLE 9 Outer Core Layer Material Rubber compound: B TAIPOL ™ BR0150 100Zinc diacrylate 29 Zinc oxide 9 Barium sulfate 11 Peroxide 1

Outer core layer 120 may be made by any suitable process. For example,in some embodiments, outer core layer 120 may be made by a compressionmolding process. The process of making the outer core layer may beselected based on a variety of factors. For example, the process ofmaking the outer core layer may be selected based on the type ofmaterial used to make the outer core layer and/or the process used tomake the other layers.

In some embodiments, outer core layer 120 may be made through acompression molding process including a vulcanization temperatureranging from 130° C. to 190° C. and a vulcanization time ranging from 5to 20 minutes. In some embodiments, the vulcanization step may bedivided into two stages: (1) the outer core layer material may be placedin an outer core layer-forming mold and subjected to an initialvulcanization so as to produce a pair of semi-vulcanized hemisphericalcups and (2) a prefabricated inner core layer may be placed in one ofthe hemispherical cups and may be covered by the other hemispherical cupand vulcanization may be completed. In some embodiments, the surface ofinner core layer 110 placed in the hemispherical cups may be roughenedbefore the placement to increase adhesion between inner core layer 110and outer core layer 120. In some embodiments, inner core surface may bepre-coated with an adhesive before placing inner core layer 110 in thehemispherical cups to enhance the durability of the golf ball and toenable a high rebound.

In some embodiments, inner core layer 110 may have a high resilience.Such a high resilience may cause golf ball 100 to have increased carryand distance. In some embodiments, inner core layer 110 may have acoefficient of restitution (COR) value ranging from 0.79 to 0.89. Insome embodiments, inner core layer 110 may have a COR value ranging from0.795 to 0.88. The COR value of inner core layer 110 may be greater thanthe COR value of golf ball 100. In some embodiments, the COR value ofinner core layer 110 may be 0.005 to 0.02 greater than the COR value ofgolf ball 100.

In some embodiments, inner core layer 110 may have a compressiondeformation value ranging from 2.5 mm to 5 mm. In some embodiments,inner core layer 110 may have a compression deformation value rangingfrom 3.5 mm to 5 mm. Inner core layer 110 may have a surface Shore Dhardness of from 40 to 60. In some embodiments, outer core layer 120 mayhave a surface Shore D hardness of from 50 to 60, which may be higherthan the surface hardness of inner core layer 110. In some embodiments,outer core layer 120 may have a surface Shore D hardness of from 45 to55.

In some embodiments, inner core layer 110 may have a Shore Dcross-sectional hardness ranging from 40 to 60 at any single point on across-section obtained by cutting inner core layer 110 in half. In someembodiments, inner core layer 110 may have a Shore D cross-sectionalhardness ranging from 45 to 55 at any single point on a cross-sectionobtained by cutting inner core layer 110 in half. In some embodiments,the difference in Shore D cross-sectional hardness at any two points onthe same cross-section may be within ±6. In some embodiments, thedifference in Shore D cross-sectional hardness at any two points on thesame cross-section may be within ±3.

In some embodiments, inner core layer 110 may have a smaller specificgravity than outer layers. Such a difference in specific gravity maycause golf ball 100 to have a greater moment of inertia. In someembodiments, the specific gravity of inner core layer 110 may range fromabout 0.85 g/cm³ to about 1.1 g/cm³. In some embodiments, the specificgravity of inner core layer 110 may range from about 0.9 g/cm³ to about1.1 g/cm³.

In some embodiments, inner cover layer 130 of golf ball 100 may have athickness ranging from 0.5 mm to 1.5 mm. For example, inner cover layer130 may have a thickness of 1 mm. In some embodiments, inner cover layer130 may have a thickness ranging from 0.8 mm to 1 mm. For example, insome embodiments, inner cover layer 130 may have a thickness of 0.9 mm.

In some embodiments, outer cover layer 140 of golf ball 100 may have athickness ranging from 0.5 mm to 2 mm. For example, outer cover layer140 may have a thickness of 1 mm. In some embodiments, outer cover layer140 may have a thickness ranging from 1 mm to 1.5 mm. For example, insome embodiments, inner cover layer 130 may have a thickness of 1.2 mm.

Outer cover layer 140 may have a thickness T1, inner cover layer mayhave a thickness T2, and outer core layer 120 may have a thickness T3.In some embodiments, T1 may be greater than T2. In some embodiments, T1and T3 may have the following relationship: 5T1≦T3≦10T1.

In some embodiments, inner cover layer 130 may have a Shore D hardness,as measured on the curved surface, ranging from about 60 to 80. In someembodiments, outer cover layer 140 of golf ball 100 may have a Shore Dhardness, as measured on the curved surface, ranging from 40 to 60. Tohave a low spin performance off the driver shot and good hitting feel,inner cover layer 130 may have a higher flexural modulus than outercover layer 140. In some embodiments, inner cover layer 130 may have aflexural modulus ranging from 50,000 psi to 100,000 psi, or from 60,000psi to 100,000 psi and outer cover layer 140 may have a flexural modulusranging from 200 psi to 3,000 psi, or from 300 psi to 2,000 psi. In someembodiments, inner cover layer 130 may have a first flexural modulus andouter cover layer 140 may have a second flexural modulus, and a ratio offirst flexural modulus to second flexural modulus (first flexuralmodulus/second flexural modulus) may range from 10 to 30. In someembodiments, ratio of first flexural modulus to second flexural modulus(first flexural modulus/second flexural modulus) may range from 25 to100. In some embodiments, the ratio of first flexural modulus to secondflexural modulus (first flexural modulus/second flexural modulus) mayrange from 95 to 250. In some embodiments, inner core layer 110 may havea third flexural modulus. In some embodiments, the ratio of firstflexural modulus to third flexural modulus (third flexuralmodulus/second flexural modulus) may range from 5 to 10. Outer cover 140having a lower flexural modulus than inner cover 130 and/or inner corelayer 110 may provide golf ball 100 with a good feel in short shots andputting shots.

In some embodiments, inner cover layer 130 and/or outer cover layer 140may be made from a thermoplastic material including at least one of anionomer resin, a highly neutralized acid polymer composition, apolyamide resin, a polyester resin, and a polyurethane resin. In someembodiments, inner cover layer 130 may include the same type of materialas outer cover layer 140. In some embodiments, inner cover layer 130 mayinclude a different type of material from outer cover layer 140.

Table 10 provides an example of materials used to make inner cover layer130, according to the exemplary embodiment. The amounts of the materialslisted in Table 9 are shown in parts by weight (pbw) or percentages byweight. Neothane 6303D is the trade name of a thermoplastic polyurethaneproduced by Dongsung Highchem Co. LTD.

TABLE 10 Inner Cover Layer Material Resin: C Neothane 6303D 100

Table 11 provides an example of materials used to make outer cover layer140, according to the exemplary embodiment. The amounts of the materialslisted in Table 11 are shown in parts by weight (pbw) or percentages byweight, as indicated. “PTMEG” is polytetramethylene ether glycol, havinga number average molecular weight of 2,000, and is commerciallyavailable from Invista, under the trade name of Terathane® 2000. “BG” is1,4-butanediol, commercially available from BASF and other suppliers.“TMPME” is trimethylolpropane monoallylether, commercially availablefrom Perstorp Specialty Chemicals AB. “DCP” is dicumyl peroxide,commercially available from LaPorte Chemicals Ltd. “MDI” isdiphenylmethane diisocyanate, commercially available from Huntsman,under the trade name of Suprasec® 1100. Outer cover materials D may beformed by mixing PTMEG, BG, TMPME, DCP and MDI in the proportions shownin Table 11. Specifically, these materials may be prepared by mixing thecomponents in a high agitated stir for one minute, starting at atemperature of about 70° C., followed by a 10-hour post curing processat a temperature of about 100° C. The post cured polyurethane elastomersmay be ground into small chips.

TABLE 11 Outer Cover Layer Materials Polyurethane: D PTMEG (pbw) 100 BG(pbw) 15 TMPME (weight % to  10% total components) DCP (weight % to 0.5%total components) MDI (pbw) 87.8 (NCO index) 1.01

In some embodiments, golf ball 100 may have a moment of inertia betweenabout 80 g/cm² and about 90 g/cm². Such a moment of inertia may producea desirable distance and trajectory, particularly when golf ball 100 isstruck with a driver or driven against the wind.

In some embodiments, golf ball 100 may include a ball compressiondeformation of 2.2 mm to 4 mm. In some embodiments, golf ball 100 mayhave compression deformation of 2.5 mm to 3.5 mm. In some embodiments,golf ball 100 may have compression deformation of 2.5 mm to 3 mm.

In some embodiments, the specific gravity of inner cover layer 130 orouter cover layer 140 may range from about 1.1 g/cm³ to about 1.45g/cm³. In some embodiments, the specific gravity of inner cover layer130 or outer cover layer 140 may range from about 1.1 g/cm³ to about1.35 g/cm³. In some embodiments, the layers used to make golf ball 100may have a specified relationship in terms of their respective physicalproperties. For example, to have greater moment of inertia, the golfball layers may have a specific gravity gradient increased from innercore layer 110 to outer cover layer 140. In some embodiments, inner corelayer 110 may have a first specific gravity, outer core layer 120 mayhave a second specific gravity greater than the first specific gravityby at least 0.01, and inner cover layer 130 may have a third specificgravity greater than the second specific gravity by at least 0.01. Insome embodiments, golf ball 100 may have the following mathematicalrelationship for specific gravity of each layer: inner core layer 110may have a specific gravity SG1; outer core layer 120 may have aspecific gravity SG2; inner cover layer 130 may have a specific gravitySG3, and outer cover layer 140 may have a specific gravity SG4, whereinSG3>SG4>SG2>SG1.

In some embodiments, golf ball 100 may have 300 to 400 dimples on theouter surface of outer cover layer 140. In some embodiments, golf ball100 may have 310 to 390 dimples on the outer surface of outer coverlayer 140. In some embodiments, golf ball 100 may have 320 to 380dimples on the outer surface of outer cover layer 140. When the totalnumber of the dimples is smaller than 300, the resulting golf ball maycreate a blown-up trajectory, which reduces flight distance. On theother hand, when the total number of the dimples is greater than 400,the trajectory of the resulting golf ball may be easy to drop, whichreduces the flight distance.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A golf ball comprising, an inner core layer; an outer core layer enclosing the inner core layer; an inner cover layer enclosing the outer core layer, the inner cover layer having a first flexural modulus; an outer cover layer enclosing the inner cover layer, the outer cover layer having a second flexural modulus; and wherein the first flexural modulus is at least 10 times greater than said second flexural modulus.
 2. The golf ball according to claim 1, wherein the ratio between the first flexural modulus and the second flexural modulus (first flexural modulus/second flexural modulus) ranges from about 10 to about
 30. 3. The golf ball according to claim 1, wherein the ratio between the first flexural modulus and the second flexural modulus (first flexural modulus/second flexural modulus) ranges from about 25 to about
 100. 4. The golf ball according to claim 1, wherein the ratio between the first flexural modulus and the second flexural modulus (first flexural modulus/second flexural modulus) ranges from about 95 to about
 250. 5. The golf ball according to claim 1, wherein the inner core layer includes a third flexural modulus and the ratio of third flexural modulus to second flexural modulus (third flexural modulus/second flexural modulus) ranges from about 5 to about
 10. 6. The golf ball according to claim 5, wherein the inner core layer includes at least one highly neutralized acid polymer composition.
 7. The golf ball according to claim 1, wherein the inner core layer has a coefficient of restitution value ranging from about 0.775 to about 0.81.
 8. The golf ball according to claim 1, wherein the inner core layer has a coefficient of restitution value that is about 0.005 to about 0.02 greater than the coefficient of restitution value of the golf ball.
 9. The golf ball according to claim 1, wherein the inner cover layer has a Shore D hardness ranging from about 45 to about
 55. 10. A golf ball comprising, an inner core layer, the inner core layer having a first flexural modulus; an outer core layer enclosing the inner core layer; an inner cover layer enclosing the outer core layer; an outer cover layer enclosing the inner cover layer, the outer cover layer having a second flexural modulus; and wherein the first flexural modulus is at least 5 times the second flexural modulus.
 11. The golf ball according to claim 10, wherein the ratio of first flexural modulus to second flexural modulus (first flexural modulus/second flexural modulus) ranges from about 5 to about
 10. 12. The golf ball according to claim 11, wherein the inner cover layer has a third flexural modulus and the ratio between the third flexural modulus and the second flexural modulus (third flexural modulus/second flexural modulus) ranges from about 10 to about
 30. 13. The golf ball according to claim 10, wherein the inner core layer includes a first highly neutralized acid polymer composition.
 14. The golf ball according to claim 13, wherein the first highly neutralized acid polymer composition includes one of HPF 2000 and HPF AD
 1035. 15. The golf ball according to claim 10, wherein the inner core layer includes a first highly neutralized acid polymer composition and a second highly neutralized acid polymer composition and the ratio of the first highly neutralized acid polymer composition to the second highly neutralized acid polymer composition ranges from about 20:80 to about 80:20.
 16. The golf ball according to claim 10, wherein the inner core layer has a coefficient of restitution value that is about 0.005 to about 0.02 greater than the coefficient of restitution value of the golf ball.
 17. A golf ball comprising, an inner core layer; an outer core layer enclosing the inner core layer; an inner cover layer enclosing the outer core layer, the inner cover layer having a first flexural modulus; an outer cover layer enclosing the inner cover layer, the outer cover layer having a second flexural modulus; wherein the first flexural modulus is at least about 45,000 psi greater than said second flexural modulus.
 18. The golf ball according to claim 17, wherein the first flexural modulus is between about 45,000 psi and about 65,000 psi greater than the second flexural modulus.
 19. The golf ball according to claim 17, wherein the first flexural modulus is between about 60,000 psi and about 95,000 psi greater than the second flexural modulus.
 20. The golf ball according to claim 17, wherein the inner core layer includes a third flexural modulus and the third flexural modulus is between about 15,000 psi to 65,000 psi greater than the second flexural modulus. 